Certain pyrazolo[3,4-b]pyridine compounds have been described in U.S. Pat. No. 3,755,340 issued Aug. 28, 1973, as being central nervous system (CNS) depressants. In particular, 4-butylamino-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester is shown and has been given the generic name cartazolate. The study of the pharmacology of cartazolate has included investigation of the metabolites formed in monkeys after its administration. Urinary metabolites having gamma-hydroxylation of the 4-butylamino side chain have been reported in Federation Proceedings, Vol. 37, page 271 (1978). Further, Column 22 of U.S. Pat. No. 3,755,340 sets forth a synthesis of 4-n-butylamino-1-ethyl-6-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester which has the generic name tracazolate.
Some of the compounds of the invention are blood metabolites of tracazolate in rats which have been found themselves to possess significant pharmaceutical activity as modifiers of CNS activity, e.g. as anxiolytics.